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Date: Tue, 12 Oct 2010 13:39:19 +0400 (MSD)
From: William Pitcock <nenolod@dereferenced.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, efault@gmx.de,
        kernel@kolivas.org
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In-Reply-To: <20101012093044.GD20366@elte.hu>
Subject: Re: [PATCH try 5] CFS: Add hierarchical tree-based penalty.
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Hi,

----- "Ingo Molnar" <mingo@elte.hu> wrote:

> * William Pitcock <nenolod@dereferenced.org> wrote:
> 
> > Inspired by the recent change to BFS by Con Kolivas, this patch
> causes 
> > vruntime to be penalized based on parent depth from their root task
> 
> > group.
> > 
> > I have, for the moment, decided to make it a default feature since
> the 
> > design of CFS ensures that broken applications depending on task 
> > enqueue behaviour behaving traditionally will continue to work.
> 
> Just curious, is this v5 submission a reply to Peter's earlier review
> of 
> your v3 patch? If yes then please explicitly outline the changes you
> did 
> so that Peter and others do not have to guess about the direction your
> 
> work is taking.

I just did that in the email I just sent.  Simply put, I was talking with
Con a few weeks ago about the concept of having a maximum amount of service
for all threads belonging to a process.  This did not work out so well, so
Con proposed penalizing based on fork depth, which still allows us to maintain
interactivity with make -j64 running in the background.

Actually, I lie: it works great for server scenarios where you have some
sysadmin also running azureus.  Azureus gets penalized instead, but other
apps like audacious get penalized too.

William